Radio Frequency Identification (RFID) Tags and Reader Antennas Based on Conjugate Matching and Metamaterial Concepts

Transcription

1 Radio Frequency Identification (RFID) Tags and Reader Antennas Based on Conjugate Matching and Metamaterial Concepts Ph.D. Thesis written by Gerard Zamora González Under the supervision of Jordi Bonache Albacete and Ferran Martín Antolín Bellaterra (Cerdanyola del Vallès), July 2013

2

3 The undersigned, Dr. Jordi Bonache Albacete and Prof. Ferran Martín Antolín, Professors of the Electronic Engineering Department (Engineering School) of the Universitat Autònoma de Barcelona, CERTIFY: That the thesis entitled Radio Frequency Identification (RFID) Tags and Reader Antennas Based on Conjugate Matching and Metamaterial Concepts has been written by Gerard Zamora González under their supervision. And hereby to acknowledge the above, sign the present. Signature: Jordi Bonache Albacete Signature: Ferran Martín Antolín Bellaterra, July 29 th 2013 iii

4

5 Contents Acknowledgements... ix Summary... xi 1 Motivation and Objectives Introduction Introduction to RFID Technology Automatic Identification Systems Operating Frequency Ranges and Applications Brief History Standardization Market Trend UHF-RFID Systems: Overview and State of the Art v

6 CONTENTS UHF-RFID Frequency Bands and Operating Principle Read Range: Definition and Measurement Lumped element Equivalent-Circuit Model of UHF-RFID Chips Physical Bandwidth Limitations: The Bode Criterion State of the Art Introduction to Leaky-Wave Antennas Based on Metamaterial Transmission Lines Metamaterial Transmisison Lines Based on SRRs Leaky-Wave Antennas References Single Resonant Passive Circuit Network for Conjugate Matching and Bandwidth Optimization Circuit Network Analysis Limitation of the 3 db Bandwidth Design of a Broadband UHF-RFID Tag Equivalent-Circuit Model for Tag Bandwidth Optimization Tag Antenna Design Fabrication and Experimental Results... 59

7 CONTENTS 3.5 Conclusions References Design and Synthesis Methodology for UHF-RFID Tags Based on the T-match Network Previous Equivalent-Circuit Models of T-match Based Tags Proposed Circuit Approach and Requirements Design and Synthesis of T-match Based Tags Design of a T-match Based Tag using a Resonant Antenna Tag Bandwidth Related to the Antenna Impedance Frequency Range of Validity of the Proposed Approach Synthesis of a T-match Based Tag using a Resonant Antenna Design of a Broadband UHF-RFID Tag using the Proposed Method Fabrication and Experimental Results Synthesis Technique of the Proposed Method Conclusions References Microwave and UHF-RFID Devices Based on Metamaterial Concepts for Reader Applications Fundamental Mode LWA using Slot Line and SRR-Based Metamaterials for vii

8 CONTENTS Microwave RFID Reader Applications Design of a Balanced CPW CRLH Transmission Line Proposed Structure Simulation and Experimental Results Automatic Vehicle Identification (AVI) Applications Design Strategy of Near Field Communication Devices for UHF-RFID Reader Applications Conclusions References Conclusions and Future Work APPENDIX A APPENDIX B APPENDIX C Author list of publications Patents

9 Acknowledgements The present work would have never been possible without the help and support of many people who helped me during the PhD, and hence this thesis is partially their merit. I have to give special thanks to my supervisors, Jordi Bonache and Ferran Martín, for their constant guidance, support and encouragement. Thank you Ferran for giving me the opportunity to start my professional trajectory as a researcher, and for your invaluable efforts, making things in my research much more understandable and simpler. Jordi, you have been the great master who has hugely contributed in my training as a researcher in the art of engineering and science. I do not find words for you, so I will simply say deep thanks. Also, I would like to thank all the members from GEMMA/CIMITEC and the Electronic Engineering Department for their support and help. Gonzalo, Jose, Paris, Núria, Albin, Miqui, Simone, G. Sisó, Naqui, Albert and J. Hellín. I have to give special mention to F. Paredes who has worked with me side by side during this period, and J. Selga for his help and patience. Thanks to my family for their kindness and affection, and to all my friends have provided me with so many laughs and good times during these last years. Of course, this is also a tribute to a very important person in my life, who knows the pains of this thesis better than I, and without whom the bad moments would have been infinitely worse: thank you Cristina. ix

10

11 Summary Radio frequency identification (RFID) is a fast developing technology that provides wireless identification and tracking capability by using simple devices used for tagging objects or people on one end, called tags, and more complex devices on the other end of the link, called readers. RFID is an emerging technology and one of the most rapidly growing segments of today s automatic identification and data capture (AIDC) industry. RFID is used for hundreds, if not thousands, of applications at present. RFID is revolutionizing supply chain management, replacing bar codes as the main object tracking system, and it is rapidly becoming a cost-effective technology. However, the design of tags able to cover the whole UHF-RFID regulated bands, providing appropriate read performance, becomes an important challenge. Also, there is a lack of systematization in the design methodology of UHF-RFID tags. Another problem which prevents a faster expansion of the UHF-RFID technology is found in the retail item management, in the difficulty of simultaneously offer the possibility of controlling items payment in stores and inventory of elements present in the store. Cost reduction is a special concern in the implementation of microwave RFID systems since they typically use active tags whose power consumption should be minimized. The main objective of this thesis is to provide solutions to the aforementioned problems, contributing to the progress and improvement of the RFID technology. This is achieved by proposing new strategies and a simple methodology for the design of UHF-RFID tags based on conjugate matching, and RFID reader antennas based on metamaterial concepts. xi

12

13 CHAPTER 1 1 Motivation and Objectives Radio frequency identification (RFID) technology is a wireless communication technology that is used to uniquely identify tagged objects or people. RFID is an emerging technology and one of the most rapidly growing segments of today s automatic identification and data capture (AIDC) industry. Whether we realize it or not, RFID is an integral part of our life. RFID is used for hundreds, if not thousands, of applications such as preventing theft of automobiles and merchandise, inventory management, collecting tolls without stopping, managing traffic, gaining entrance to buildings, automating parking, controlling access of vehicles to gated communities, corporate campuses and airports, dispensing goods, providing ski lift access, tracking library books, and the growing opportunity to track a huge amount of assets in supply chain management. RFID is revolutionizing supply chain management, replacing bar codes as the main object tracking system. RFID technology is also being used in U.S. Homeland Security with applications such as securing border crossings and freight container shipments. RFID is rapidly becoming a cost-effective technology. This is in large part due to the efforts of Wal-Mart (the world s largest retailer) and the U. S. Department of Defense (the world s largest supply chain operator) to incorporate RFID technology into their supply chains. 1

14 CHAPTER 1 MOTIVATION AND OBJECTIVES In recent years, the applications of RFID passive systems operating in the UHF band have experienced a progressive growth. UHF-RFID tags are usually designed to operate at a single frequency band. However, due to the different worldwide regulations, the UHF-RFID frequency bands have different locations in the spectrum and vary in the different world regions. Therefore, the design of UHF-RFID tags able to cover the whole regulated bands (i.e., global band tags), providing appropriate read performance, becomes an important challenge. Another major problem which prevents a faster expansion of the UHF-RFID technology at present is found in a potential application from which high expectations arises: the retail item management. The problem is found in the difficulty of simultaneously offer the possibility of controlling items payment in stores and inventory of elements present in the store. Cost reduction is of special concern in the implementation of microwave RFID systems since they typically use active tags, which are powered by means of a battery, and power consumption should be minimized. The main objective of this thesis is to provide solutions to the aforementioned problems, thus contributing to the progress and improvement of the RFID technology. This will be achieved by providing new strategies for the design of UHF-RFID tags based on conjugate matching, and microwave and UHF-RFID reader antennas based on metamaterial concepts. Accordingly, the outline of this work is as follows: The second chapter presents an overview of RFID technology, paying special attention to UHF-RFID systems. The concept of metamaterials is defined and metamaterial transmission lines based on a coplanar waveguide (CPW) transmission line and SRRs are introduced. Leaky-wave antennas (LWAs) based on metamaterial transmission lines are also described. In chapter three, the passive circuit network required for tag bandwidth broadening, by introducing a single resonance with conjugate matching at the intermediate frequency of the UHF-RFID band is obtained. According to this analysis, a global band UHF-RFID tag prototype is designed and fabricated. In chapter four, a new method for the design of global band UHF-RFID tags based on the T-match network is proposed. Such method is based on the equivalent-circuit network for bandwidth broadening obtained in Chapter 3. As a proof of concept, a global band tag is designed using this method and fabricated. Chapter five is focused on the design of RFID devices based on metamaterial concepts for reader applications. A leaky-wave antenna (LWA) is proposed to be used as microwave RFID reader antenna in the field of automatic vehicle identification (AVI). Moreover, a new methodology for designing near field (NF) 2

15 2.1 INTRODUCTION TO RFID TECHNOLOGY communication devices able to confine the electric and magnetic field in a controlled coverage region is presented for applications in the retail item management. Lastly, in chapter six, the conclusions and future research that result from this thesis are outlined. The work conducted during the realization of this thesis was carried out within the Group GEMMA/CIMITEC, which is part of the Electronics Engineering Department of the Universitat Autònoma de Barcelona. GEMMA/CIMITEC has been part of the European Network of Excellence NoE METAMORPHOSE (Metamaterials organized for radio, millimeter wave and photonic super lattice engineering), the main objective of which was to research, study and promote artificial electromagnetic materials and metamaterials within the European Union. It has recently given rise to the Virtual Institute for Artificial Electromagnetic Materials and Metamaterials (METAMORPHOSE VI AISBL). Furthermore, CIMITEC is one of the centers of the Technological Innovation Network of TECNIO (ACC1Ó) of the Catalan Government, created with the objective of promoting the transference of technology to industry in the field of Information and Communication Technology and has been recognized as a Consolidated Group by the Catalan Government (AGAUR). This work was, thus, supported by the European, Spanish and Catalan Governments by means of several projects and contracts. Among the projects and contracts with the different institutions and companies that have given support to the developed research activities, we would like to highlight: International Project Eureka METATEC granted to a consortium composed of two companies and three research institutions from Serbia and Spain and funded in Spain by a PROFIT and an AVANZA I+D project. Title: METAmaterial-based TEchnology for broadband wireless Communications and RF identification. This project is linked to the following two projects. Period: Project FIT funded by the Spanish Government (Ministerio de Industria, Turismo y Comercio) by a PROFIT project. Title: Metamaterial-based technology for broadband wireless communications and RF identification. Period: Project TSI funded by the Spanish Government (Ministerio de Industria, Turismo y Comercio) by a AVANZA I+D project. Title: Metamaterialbased technology for broadband wireless communications and RF identification. Period: Project TEC C02-02 METAINNOVA from the Spanish Government (Dirección General de Investigación). Project coordinated by the Universitat 3

16 CHAPTER 1 MOTIVATION AND OBJECTIVES Autònoma de Barcelona and the Universidad de Sevilla. Title: Tecnologías basadas en metamateriales y su aplicación a la innovación en componentes y subsistemas de RF microondas y milimétricas: circuitos de radiocomunicación. Period: Project CSD CONSOLIDER INGENIO 2010 granted to a consortium composed of eight research groups from different Spanish Universities and funded by the Spanish Government. Title: Ingeniería de Metamateriales (EMET). Period: Project TSI funded by the Spanish Government (Ministerio de Industria, Turismo y Comercio) by a AVANZA I+D project. Title: Implementación de etiquetes de identificación por radio frecuencia de reducidas dimensiones y altas prestaciones. Period: Project TEC METATRANSFER granted to the Universitat Autònoma de Barcelona by the Spanish Government. Title: Nuevas estrategias de diseño y síntesis de componentes de microondas basados en conceptos de METAmateriales con orientación a la TRANSFERencia tecnológica. Period:

17 CHAPTER 2 2 Introduction In this chapter, the main characteristics of RFID technology are introduced, as well as a brief history and a market prediction for the near future. RFID systems operating within the UHF regulated frequency bands are explained with more detail, including the most relevant features and the state of the art of such technology. Next, the concept of metamaterials is defined and metamaterial transmission lines (MTM TLs) based on a coplanar waveguide (CPW) and split ring resonators (SRRs) are described. Finally, leaky-wave antennas (LWAs) are briefly described, focusing the attention on planar implementations using MTM TLs, since a LWA based on metamaterial concepts is proposed in Chapter 5 for RFID reader applications. 2.1 Introduction to RFID Technology Radio frequency identification (RFID) is a fast developing technology that provides wireless identification and tracking capability. Nowadays, many applications such as preventing theft of automobiles and merchandise, collecting tolls without stopping, gaining entrance to buildings, controlling access of vehicles to gated communities, corporate campuses and airports, providing ski lift access, tracking library goods, asset 5

18 CHAPTER 2 INTRODUCTION Fig. 2.1 The basic building blocks of an RFID system, including a host controller. Fig. extracted from [2]. identification, retailing and supply chain management, animal tracking, among others, take advantage of RFID systems [1],[2]. This section gives an overview of RFID technology and includes a short explanation about the main operating frequency ranges, as well as a brief history of RFID and the market trend. RFID is generally characterized by the use of simple devices on one end, called tags or transponders, and more complex devices on the other end of the link, called readers or interrogators. The tags are made up of an antenna and an application specific integrated circuit (ASIC) chip, which contains memory where data is stored. Occasionally, they can include a matching network, located in between the antenna and the chip, to achieve proper impedance matching. The readers are composed of an antenna, an RF electronic module, which is responsible for communicating with the tag, and a control electronic module, which is responsible for communicating with a host computer (or controller), usually connected to the reader in order to centrally process information coming from readers. Fig. 2.1 shows the schematic of a typical RFID system. RFID systems can be read only (data is transferred in one direction, from the tag to the reader) or read-write (two way communication). Tags can be powered by a battery (active tags) or by rectification of the radio signal sent by the reader (passive tags). This thesis delves into passive RFID systems Automatic Identification Systems Auto-ID (Automatic Identification) technology, also called automatic identification and data capture (AIDC), is a big set of identification procedures which include the very well-known barcode, as well as Optical Character Recognition (OCR), infrared identification and RFID. Among the various forms of Auto-ID, optical barcodes clearly 6

19 2.1 INTRODUCTION TO RFID TECHNOLOGY (a) (b) Fig. 2.2 (a) Traditional one-dimensional barcode (UPC code) and (b) two-dimensional barcode (QR code). dominate the Auto-ID market being used in almost everything and everywhere today in the world. The main reason is their ultra-low cost, which is almost negligible. However, they are limited in memory storage capability and line-of-sight operation is required. The latter makes the presence of an operator necessary to read a barcode. Since RFID systems do not have these limitations and, therefore, remove the human intervention in the reading process, RFID technology is coming into the Auto-ID market with a huge potential. In addition, unlike barcodes, RFID technology provides security by means of data encryption, and read/write capability. Nevertheless, RFID tags require a chip to store the data, which makes the tags expensive to be implemented in certain Auto-ID market applications. Barcodes typically cost under 0.01, whereas RFID tags cost over 0.10, as indicated in Table 2.1 where a comparison between optical barcodes and RFID systems is shown [2],[3]. Thus, there is a big demand of low-cost RFID technology around the world, and it is believed that someday RFID tags will be as pervasive as barcodes. Table 2.1 Comparison of barcode vs. RFID system characteristics Barcode RFID Data Transmission Optical Electromagnetic Memory/Data Size Up to 3 KB Up to 64 KB (passive tags) Up to 128 KB (active tags) Tag Writable No Possible Position of Scan/Reader Line-of-sight Non-line-of-sight possible Read range Typically up to several cm Up to 15 m (passive tags) Up to > 100 m (active tags) Access Security Low High Environmental Dirt Low Susceptibility Multiple reading Not possible Possible Price < 0.01 From 0.1 to 1 (passive tags) From 10 to 100 (active tags) 7

20 CHAPTER 2 INTRODUCTION Operating Frequency Ranges and Applications RFID systems operate at widely different frequency bands, as shown in Fig. 2.3, including frequencies from 125 KHz to 5.8 GHz in the microwave range. There are four main frequency bands used in RFID technology [2],[3]: Low frequency (LF). These systems operate between 125 KHz and KHz being available for use in the United States, Europe and Japan. Due to the electromagnetic properties at these frequencies, LF tags can be read even when they are attached to objects containing water, animal tissues, metal, wood, and liquids. However, they are only suitable for proximity applications, because they can be interrogated from a very short range of only a few centimeters (generally LF tags are passive). LF tag antennas are usually made of a copper coil with hundreds of turns rolled around a ferrite core. Because of these properties of LF tags, they are used for specific applications such as animal identification, access control, asset tracking, vehicle immobilizer, healthcare, and various point-of-sale applications. In particular, LF tags have been intensively used for animal tracking since the early 1980s. High frequency (HF). Working around a central frequency of MHz, this frequency band is also available for use in the United States, Europe and Japan at very similar power levels. HF tags are passive and their operating principles are similar to LF tags. However, HF tags have a better read range than LF tags and can be read up to half a meter away. The tag includes an LC resonant antenna usually made of several turns (~ 5-20 turns) of conductive materials such as copper, aluminum, or silver as a flat 8 Fig. 2.3 Main RFID frequency bands and photographs of typical tags.

21 2.1 INTRODUCTION TO RFID TECHNOLOGY Fig. 2.4 Examples of LF-RFID tags for animal tracking (left) and vehicle immobilizer (right). spiral, connected to a capacitor. Therefore, HF tags are usually very thin (as thick as paper). As it occurs with LF tags, HF tags can be easily read while attached to objects containing water, tissues, metal, wood, and liquids. Their performance, however, is affected by metal objects in the close vicinity. Tagging metal objects is not possible since metals cancel significantly the magnetic field perpendicular to the object, which is required to excite HF tags attached on metal surfaces. Their Applications include nearfield communications (NFC), credit cards, smart cards, library book tags, airline baggage tags, and asset tracking. Ultra high frequency (UHF). These systems operate in the vicinity of 433 MHz (active tags) and from 840 MHz to 960 MHz (passive and semi-passive tags). There are significant differences between regulations in different countries around the world, such as the United States, Europe, China and Japan. UHF tags have a read range of up to 15 m approximately. Unlike LF and HF tags, all the protocols in the UHF range have some type of anti-collision capability, allowing multiple tags to be read simultaneously. The UHF tag antennas are mostly based on dipole antennas and made of copper, Fig. 2.5 Some applications of the NFC technology using a mobile phone. 9

22 CHAPTER 2 INTRODUCTION (a) Fig. 2.6 Examples of UHF-RFID applications in (a) supply chain management and (b) retail item management. (b) aluminum, or silver deposited on the substrate. The length of a resonant half-wave dipole antenna at 900 MHz is approximately 17 cm. However, the overall antenna size can be reduced through proper design techniques. The UHF antennas are easy to manufacture and, as HF tags, can be made thin using planar design. UHF tags offer more memory size and better read range, in comparison with LF and HF tags. As it is well-known, UHF tag performance changes when it is placed on different objects. This can generally be solved by taking into account the content on which the tag will be placed in the design stage. However, objects containing metals and water may degrade even more the read range of the tag through energy absorption and detuning. This problem can be overcome by designing tags specifically for tagging metal contents or for liquid contents. However, tags mountable on metallic objects that exhibit good performance are usually too expensive, big and occasionally heavy for certain applications. The reason of the efficiency degradation of common tags (not specially designed for metals) due to metal objects is that most UHF tags need to be excited by an electric field, tangentially oriented to the object metal surface, which extremely cancels such field. Regarding water (or liquid) contents, UHF s short wavelengths tend to get highly absorbed by liquids. Applications of UHF-RFID systems include supply chain management, retail item management and parking access control. (UHF-RFID technology will be explained with more detail in Section 2.2). Microwave. The systems operating around the central frequencies of 2.45 GHz and 5.8 GHz industrial, scientific and medical (ISM) bands fall into this category. Passive, semi-passive and active tags are available in this frequency range and in most regions. The read range for passive tags are similar to UHF tags (up to around 15 m), whereas active ones can be read within a maximum range of up to more than 100 m. Their performance can be degraded when tags are close to water or metals, just like UHF tags. 10

23 2.1 INTRODUCTION TO RFID TECHNOLOGY (a) (b) Fig. 2.7 Examples of Microwave-RFID applications in (a) highway toll collection and (b) automatic vehicle identification. Multiple tags can also be read at the same time since anti-collision protocols exist. Nonetheless, other microwave devices sharing the same ISM band such as WLAN, cordless phones and microwave ovens, provide RF noise. Among their applications, highway toll collection, fleet identification, controlling access of vehicles to gated communities, hospitals, corporate campuses and airports and real-time location systems (RTLS) must be pointed out. The most common physical coupling method used in LF and HF is based on inductive coupling, although there are also a few systems with capacitive coupling. The main reason is that magnetic field is affected only by objects with high magnetic permeability and metals, and such objects are not common in everyday life. On the other hand, capacitive coupling systems are affected by objects with high dielectric permittivity and loss. By contrast, UHF and microwave systems are coupled using electromagnetic fields and, occasionally, surface acoustic waves (see Fig. 2.8). (a) (b) Fig. 2.8 Physical coupling method based on (a) near-field magnetic induction, used in LF and HF systems, and (b) far-field electromagnetic coupling, used in UHF and microwave systems. 11

24 CHAPTER 2 INTRODUCTION Brief History The first landmark work on the basic principles of passive RFID technology was published by Harry Stockman in 1948, and it was titled Communication by Means of Reflected Power [4]. In [4] Stockman stated: Evidently, considerable research and development work has to be done before the remaining basic problems in reflectedpower communication are solved and before the field of useful applications is explored. Indeed, it took thirty years of investigation before the first RFID transponder was developed. Following, some of the most relevant events in the context of the history of RFID are chronologically listed [5]. During the 1950s, many of the technologies related to RFID were explored by researchers, taking advantage of developments in radio frequency communications and radar theory carried out in the 1930s and 1940s. In the 1950s, the U.S. military began to implement an early form of a long range identification system called identification, friend or foe (IFF), designed to distinguish between allied and enemy aircrafts. RFID technology commercial activities were beginning in the 1960s, thanks largely to the works on electromagnetic theory by R.F: Harrington, including Fields Measurements Using Active Scatterers [6] and Theory of Loaded Scatterers [7] published in 1963 and 1964, respectively. In this decade, electronic article surveillance (EAS) equipment for anti-theft and security applications was developed. These systems were 1-bit systems which allowed only detect the presence of objects, rather than identify them. The RFID explosion took place in the 1970s, when companies, academic institutions, and government laboratories were increasingly working on RFID. During this decade RFID developments were applied to animal tracking, vehicle tracking and factory automation. An important development was published in a paper titled Short-Range Radio-Telemetry for Electronic Identification using Modulated Backscatter [8], written by Alfred Koelle, Steven Depp and Robert Freyman, in By 1978, a passive microwave transponder had already been accomplished. In the 1980s, commercial RFID systems began to extend in various parts of the world. Examples include livestock management, keyless entry, personnel access systems, and transportation applications, which appeared late within this decade. The world s first toll application emerged in Europe in 1987, followed by the United States in In this same period, the development of the personal computer (PC) gave rise to a rapid expansion of RFID applications, since it made possible a more convenient and economical collection and management of data from RFID systems. Tags using custom CMOS integrated circuits and discrete components started to be built. This allowed further reductions in the size 12

25 2.1 INTRODUCTION TO RFID TECHNOLOGY of tags and increase in functionality. Consequently, the antenna size started to be crucial in determining the size of the tags. Also, the 1990s were an important decade for RFID since it began to enter the mainstream of business and technology. RFID systems began to be used for toll collection, access control and a wide variety of other applications in commerce. In mid- 1990s, RFID toll systems were operating at highway speeds enabling vehicles to pass toll collection points, unimpeded by plazas or barriers. The success of electronic toll collection led to important advancements, such as the first use of tags across different business segments. This allowed a single tag to be used for different applications such as electronic toll collection, parking lot access and gated community access. New RFID applications were also created for dispensing fuel, ski pass systems and vehicle access systems. For the first time, microwave RFID tags containing only a single integrated circuit (capability previously limited to inductively coupled RFID transponders) were constructed. This together with the rapid expansion of PC s and internet left the RFID industry with the unique problem of expensive tags to overcome, in order to develop commercially viable systems. In 1999 the Auto-ID centre was established at the Massachusetts Institute of Technology to gather RFID manufacturers, researchers and users, in order to develop standards and guidelines, together with other standard organizations including the European Conference of Postal and Telecommunications Administrations (CEPT) and the International Standards Organization (ISO). By the early 2000s microwave tags were built as adhesive labels consisting of only two components: a simple integrated circuit and an antenna. Since then, the size of tags is clearly limited by the size of the antenna. In 2003, the Auto-ID was merged into EPC (Electronic Product Code) Global and assumed the task of standards for supply chain applications. The ISO also had very active standards activities for a variety of application areas in the beginning of the 2000s. Currently, all of these organizations are working on standards for RFID technology Standardization The huge amount of applications where RFID is used and the necessity of interoperability between different systems demands a standardization of the RFID technology. The purpose of RFID standards is to create uniformity in the RFID industry and, therefore, to improve the efficiency of RFID systems and increase the industry 13